Every designer has to make a dozen decisions in each project he’s working on. Those decisions have a power to kill or resurrect a business. BTW most of them are completely powerless …
But for your manager/client is everything important. So he needs to trust you that you’ll do it the right way. If he does not then you will end up in a whirl of neverending edits. And that’s a nightmare.

So first of all earn their trust by your previous results… and then let’s go back to design ;-)